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every Degree of the Meridian therefrom to the Poles; fuch are the Tropics, and Polar Circles.

XLI. The Latitude of a Place is its Diftance from the Equator reckoned in Degrees and Minutes on the Arch of the Meridian; thus the Latitude of Z is the Arch of the Meridian Æ Z, equal to 51° 32'.

XLII. The Declination of the Sun, Moon, or Stars, is the fame as the Latitude of Places; being only their Distance North or South from the Equinoctial, in Degrees and Minutes.

XLIII. The Poles of the Ecliptic are two Points 23° 29′ diftant from the Poles of the World; as G and T.

XLIV. The Latitude of the Sun, Moon, and Stars, is their Distance from the Ecliptic towards either of its Poles, in Degrees and Minutes, counted in a proper Circle of Latitude.

XLV. Circles of Latitude or Longitude are Great Circles concurring and interfecting each other in the Poles of the Ecliptic; and crofs the Ecliptic at Right Angles; as TYG.

XLVI. The Longitude on the Terreftrial Globe is counted in Degrees and Minutes on the Equator, from Weft to Eaft. So that the Longitude of a Place is an Arch of the Equator contained between the First or General Meridian, and the Meridian paffing thro' the faid Place.

XLVII. The Longitude of the Sun, Moon, or a Star, is its Distance counted in the Ecliptic from the first Minute of Aries y, according to the Order of the Signs, to the Place where the Circle of Longitude, paffing thro' the Star, interfects the Ecliptic.

XLVIII. The Altitude of the Sun, or Stars, is the Arch of an Azimuth (in Degrees and Minutes) contained between the Center of the Sun or Star, and the Horizon.

XLXIX. Afcen

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XLIX. Afcenfion and Defcenfion is the Rifing and Setting of the Heavenly Bodies above or below the Horizon.

L. Right Afcenfion is the Number of Degrees and Minutes in the Equinoctial (from the Beginning of Aries) which cometh to the Meridian with the Center of the Sun or Star, or any Point of the Ecliptic.

LI. Oblique Afcenfion is the Arch of the Equinoctial contained between the Beginning of and r the Horizon at the moment the Sun, Star, or any. Part of the Ecliptic rifeth; on the contrary,

LII. Oblique Defcenfion is that Degree and Minute of the Equinoctial that fetteth with the Sun, Moon, Star, &c.

LIII. Afcenfional Difference, is the Difference between the Right and Oblique Afcenfion of the Sun, &c. or it is the Time which the Sun rifeth or fetteth before or after Six a-Clock; which, on the longest Day, is represented by the Arch of the Equinoctial, Ca.

LIV. The Amplitude of the Sun, or Stars, is the Distance of their Rifing or Setting from the Eaft or West Points of the Horizon, in Degrees and Minutes, toward the North or South Points thereof; and is reprefented by Cb, on the longest Day; and CD, on the shortest. The Amplitude of Rifing is alfo called the Amplitude Ortive, and the Amplitude of Setting, the Occafive Amplitude.

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Thefe are the Fundamentals on stance of the following Tract of Spher. does depend. And that the Reader mig perceive the Meaning and Purport of each. I have hereto fubjoin'd a few Schemes fo. luftration, to which I have all along referred. And though no Perfon can pretend to ftudy this kind of Science without a previous Knowledge of those VOL. II.

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Things,

Things, which are the fubject Matter of the foregoing Definitions; yet if he hath no other Expedient than bare reading of their Definitions, and viewing projected Schemes, he muft have an exceeding happy Genius ever to acquire a perfect Notion of them by this Means only.

And therefore it behoves every one, who would make any tolerable Proficiency in this Part of Knowledge, to qualify himself, as directed in the Preface to this Book, at least fo far as he is capable and hath Opportunity.

CHA P. II.

Theorems ferving to the Orthographical Projection of the Sphere, called the Analemma.

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THEOREM I.

HE Rays of Light by which the Eye, placed at an infinite Distance, beholds an Object, differ infinitely little from Parallel Rays.

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